Radio signaling system



July 21, 1931'. c. A, BODDIE ET AL 1,815,045

RADIO SIGNALING SYSTEM Filed July 50, 1928 2 Sheets-Sheet 1 F/aoa 11/37/11:

INVENTOBS Clarence A. BOddlE and Richard C. Curtis ATTORNEY Jul 21, 1931. c. A. BODDIE ET AL RADIO SIGNALING SYSTEM Filed July 30, 1928 2 Sheets-Sheet 2 di m W INVENTORS Clarence A Boddie and Richard C.Curfis BY A w I ATTORNY Patented July 21, 1931 UNITED STATES PATENT OFFICE CLARENCE A. BODDIE AND RICHARD C. CURTIS, OF WILKINSBURG, PENNSYLVANIA,

ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A COR- PORATION OF PENNSYLVANIA RADIO SIGNALING SYSTEM Application filed July 30, 1928.

Our invention relates broadly to radio signaling systems, and more particularly to systems of the type wherein an incoming radio signal is utilized to control the appli- '8 cation of energy from a local source to mechanisms of any desired character.

Although capable of many secondary applications, our invention is primarily directed toward providing radio-controlled means for illuminating an airplane landing field, upon the approach thereto of an airplane or an analogous aerial vehicle.

Obviously, it is highly important that the pilot of an aerial vehicle shall be able to distinetly see the ground upon which his ship is about to land, although the field is perfectly familiar to, him, since the presence of even relatively minor obstructions may cause a serious accident.

29 For this reason, when an airplane is about to land at night, the field upon which it is descending should be brightly illuminated, and powerful flood-lights are usually provided for this purpose. In addition to the flood-lights, the boundariesof the field are generally designated by permanently illuminated beacons which are relatively inexpensive to operate.

The power consumed by the flood-lights, however, is considerable, and it is not economical to keep them illuminated except at such times as an airplane is landing or is about to land. It has, accordingly, been proposed to provide a device which shall be sensitive to the characteristic sounds sent out from an airplane when in flight, and to so arrange the flood-lights that they are automatically turned on by the sensitive device when it is energized by the said characteristic sounds.

A sound-controlled system, however, is subject, to some extent, to accidental operation by the sounds from motor-vehicles passing by the landing field, and it is not thoroughly reliable during periods of atmospheric disturbance, such as wind storms and the like.

It is accordingly, an object of our invention to provide an air-port flood-light sys- 50 tem that shall be controlled by radio signals.

Serial No. 296,298.

Another object of our invention is to provide an air-port flood-light system wherein the supply of energy to the lamps may be controlled by an aviator, even though his airplane is distant from the landing field, thus enabling him to more readily locate the said field than if the lights were controlled solely by sound.

Another object of our invention is to provide an air-port flood-light system that shall respond only to definite radio signals, and one that shall be insensitive to disturbances.

In practicing our invention, we provide a radio receiver which is maintained in a state of oscillation, in the well-known manner, during any period of the night that the flood-lights are necessary. The output circuit of the radio receiver is arranged to actuate a series of relays which, in a manner hereinafter specifically described, control the application of power to the floodlights. The airplane may send out signals at a definite frequency for a definite length of time, or it may send out coded signals in the proper sequence to cause the actuation of a selector device. The latter method is less desirable, since it requires too much attention on the part of the aviator, whereas the former method requires merely the closing and opening of a switch.

The noval features that we consider characteristic of our invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with further objects and advantages thereof, will best be understood by reference to the following description of certain specific embodiments, taken with the accompanying drawings, in which:

Figure 1 is a diagrammatic view of an air-port flood-light system comprising a preferred embodiment of our invention, and

Fig. 2 is a diagrammatic view of a floodlight system comprising an alternative embodiment of our invention.

The system illustrated in Fig. 1 may, for purposes of convenience, be considered as comprising a portion adapted to derive a series of direct-current impulses from a continuous incoming radio signal, and a portion responsive only to a predetermined number of such impulses.

The impulse-deriving portion includes an antenna 1 which is connected to ground through a variable condenser 2 and an inductor 3. The inductor 3 is comprised in the input circu t of a thermionic device-4 of the usual three-electrode type, the input circuit also including a grid-condenser 5 and a grid-leak 6 in order that the device shall function as a detector. A plurality of condensers 7 and 8 are connected in shunt to the inductor 3, the condenser 7 being so arranged that its capacitv is periodically varied by means of a small constant-speed motor 9. The motor may be supplied with energy from a direct-current source 10, or it may be energized by alternating current.

Although we have illustrated the thermionic detector device 4 as being directly connected in the antenna-ground circuit, the exact manner in which the incoming signals are impressed upon the detector forms no part of the present invention. The detector may, if desirable, be preceded by a plurality of stages of radio-frequency amplification, wave-filters of various types may be utilized for the purpose of adding selectivity, or a loop may be used for reception purposes without departing from the spirit of our invention.

The output circuit of the thermionic device 4 includes a source 11 of high potential, the primary winding 12 of a coupling-transformer 13, and a tickler-coil 14 disposed in inductive relation to the inductor 3. A condenser 15 is connected in shunt to the wind ing 12 for a purpose hereinafter referred to.

The secondary winding 16 of the coupling transformer is comprised in the input circuit of a thermionic amplifier device 17, the output circuit of which is coupled, through a transformer 18, to the input circuit of a thermionic device 19, which device is provided with a grid leak 20 and a grid condenser 21, and, accordingly, functions as a detector.

The filaments of the several thermionic devices are connected in parallel across a source 22 of filament potential, and plate potential for the thermionic devices 17 and 19 is also supplied from the high-potential source 11.

The output circuit of the second detector device 19 includes the winding 23, of a fast relav 24, the armature 25 of which is connected to ground. One terminal of the winding of a second fast relay 26 is connected to the fixed contact 27 of the relay 24, the other terminal being connected to ground through a battery 28.

. The relay 26 is provided with a front contact 30, a back contact 31, which is normally closed, and a grounded armature 32. The

front contact 30 is connected to ground through the winding of a slow relay 33 and a battery 34, and a connection 35 extends from the back contact 31 to a front contact 36 of the said slow relay, which is of the multi-contact type, having a plurality of ar matures 37' and 38. The armature 37 is directly grounded, while the armature 38 is connected to ground through the winding of a selector stepping magnet 40 and a battery 41.

A connection 42 extends from a back contact 43, associated with the armature 38, to a back contact 44 normally in engagement with the armature 45 of the selector stepping magnet 40.

A plurality of Wipers 46 and 47, mechanically connected but electrically separate, are arranged to be actuated in a step-by-step manner over contact banks 48 and 50 individual thereto, by the selector stepping magnet 40, in a manner familiar to those skilled in the art. The contacts of the bank 50 are conductively connected together, and are grounded, while the contacts of the bank 48 are not inter-connected with each other.

The wiper 46 is connected to a front contact 51 of the relay 33, and a connection extends from the armature 45 of the magnet 40 to the wiper 47.

A single contact 52 of the bank 48 is con-,

nected to ground through the winding of a fast relay 53, of the multi-contact type, and a battery 54. A front contact 55 and an armature 56 of the relay 53 are included in a circuit which extends between a power source 57 and a plurality of fioodlights 58. An additional contact 59 and a grounded armature 60, together with a reset switch 61, are interposed in a locking circuit for the relay 53.

In the operation of the system illustrated in Fig. 1, the condenser 8 is adjusted to tune the input circuit of the first thermionic device 4 to approximately the frequency at which the airplanes send out the control signals. The size of the moving element of the condenser 7 is so chosen that it serves, when actuated by the motor, to vary the tuning of the input circuit by an amount sufficient to cover any departure from normal frequency which the airplane transmitters may make.

It is, of course, feasible to assign to the airplanes adefinite frequency band, and, in such event, the motor-driven condenser causes the tuning of the receiver to vary continuously between the upper and lower limits of the said band.

The speed of rotation of the motor is so chosen that the tuning range of the receiver is covered in less time than is required for the slow relay 33 to release.

The receiver is maintained in the oscillatory state by proper adjustment of the III tickler coil 14. If therefore, signals at a frequency within the range of variation of tuning occasioned by the motor-driven condenser 7, are impressed upon the input 011- cuit of the receiver, a beat note will be caused by the interaction of the locally generated oscillations and the incoming signals. The beat note will vary, in frequency, as the tuning of the receiver approaches coincidence with the frequency of the incoming signals and departs therefrom. At the exact instant when the frequency of the local oscillations is equal to that of, the incoming signal, the beat note will be inaudible.

In order that a' single impulse shall be transmitted from the receiver to the subsequent relays for each revolution of the motordriven tuning condenser, 7, condenser 15, which is connected in shunt to the primary Winding 12 of the output transformer 13, is chosen of such size as to tune the said winding to a definite frequency, the frequency of 1000 cycles per second being chosen as illustrative.

Each time, therefore, that the locally generated oscillations differ, in frequency, by 1000 cycles from the frequency of the incoming signals, an impulse will be transmitted to the amplifier tube 17, amplified therein, and impressed upon the input circuit of the second detector tube 19.

The plate current in the second detector device is so adjusted that it is normally sufficient to maintain the contacts of the relay 24 open. When, however, a signal at, say 1000 cycles, is impressed on the input circuit of the thermionic device 19, the plate current in the said device is reduced in magnitude so long as'the input excitation persists.

Each time, therefore, that the beat note is impressed on the thermionic device 19, the armature 25 of the relay 24 is released, the relay 26 is momentarily energized, and ground is applied to the contact 30 to energize the slow relay 33. Upon excitation of the slow relay, the armature 37'pulls in to place ground upon the'wiper 46, and the armature 38, by engaging the contact 36, completes a circuit from the back contact 31 of the fast relay 26, through the winding of the selector stepping magnet and the battery 41, to ground.

The slow relay 33, once being energized, will not release during the intervals of operation of the two fast relays 24 and 26 since, as was pointed out previously, the speed of rotation of the motor is so chosen that successive beat notes will follow each other at intervals shorter than the time required for the said slow relay to release.

It is, accordingly, apparent that an impulse is applied to the selector stepping magnet 40 every time the armature 32 of the fast relay 26 drops out to engage the back contact 31, the interval between the impulses being determined by the speed of rotation of the motor 8.

The wiper 46, therefore, continues to advance just so long as the incoming signal is being received. Upon reaching the contact 52, to which the winding of the. relay 53 that controls the flood lights is connected, an energizing circuit is established for the said relay. The energizing circuit may be traced from the battery 55 to ground, from ground to the armature 37 and the contact 51 of the slow relay 33, thence to the wiper 46, and, through the winding of the relay, back to the opposite pole of the battery 54.

To deenergize the light-control relay, it is only necessary to actuate the re-set switch 61 which is included in the holding circuit established for the said relay through the armature 60 and the contact 59.

In the event that a continuous series of impulses is notimpressed upon the slow relay 33, the said relay releases the armature 38. A circuit is, accordingly, established through the wiper 47, which permits the stepping magnet 40 to operate as a buzzer to advance the wipers 47 and 48 until the wiper 47 is brought to engagement with a bank contact which is not connected to ground, thus deenergizing the stepping magnet and preparing the system for subsequent actuation.

Instead of utilizing a selector device for assuring a sufficient time-delay between the first reception of the radio signals and the energization of the flood-lights, in order to prevent discontinuous interfering impulses from actuating the system, it lies within the province of our invention to make use of any well known slow-acting relay for this purpose. An alternative form of our invention, in which selector devices are dispensed with, is illustrated in Fig. 2 of the drawings, in which figure, the elements analogous to those of Fig. 1 are similarly numbered.

In the alternative form of our invention, the oscillatory first detector 4, the audiofrequency amplifier 17, the second detector 19, and the fast relay 24, are arranged in the manner hereinbefore described in connection with Fig. 1. The back contact 27 of the relay 24 is connected to ground through the winding of a multi-contact fast relay and a battery 71. The fast relay 70 is provided with two armatures, 72 and 73, both of which are grounded. A front contact 74 of the fast relay 70 is connected to ground through the winding'of a slow relay 75, of the multi-contact type, and a battery 76.

A front contact 77 of the slow relay is connected to a back contact 78 of the fast relay 70, and the armature 80, associated with the said front contact, is connected to ground through the winding of a second slow relay 81 and a battery 82. A front contact 83 of the fast relay is connected to a back contact 84 of the last mentioned slow relay 81, and the armature 85 associated with the said back contact is connected to ground through a solenoid 86 which has a movable core 87. The speed at which the core 87 rises upon energizing the solenoid is determined by the adjustment of adashpot 88, or by an equivalent device.

A grounded, movable armature 90 is dis posed in the path of travel of the movable core 87. A fixed contact 91 analogous, in function, to the contact 52 of the bank 48 shown in Fig. 1, is associated with the movable arinature 90. The contact 91 is connected to ground through the winding of the floodlight control relay 53 and the battery 54. The winding of the relay 53 is also connected to a front contact 59 thereof by way of the reset switch 61, as previously described, toprovide a locking circuit for the relay.

A. back contact 92 of the slow relay 75 and a front contact 98 of the slow relay 81 are connected in parallel to a conductor 94 included in the power-supply circuit for the condenser-driving motor 9. The armatures 95 and 96 of the said slow relays are connected to a conductor 97 which is also included in the said power-supply circuit, thus placing the motor 9 under the control of either of the slow relays.

In order to put the system just described into receptive condition, the receiver is energized, and the tickler coil 1% so adjusted that oscillations are generated. The motor 9 is started, and its speed is so regulated that the tuning of the receiver is slowly varied over the frequency-band assigned to the airplane transmitters.

Upon the receipt of a continuous-Wave signal from an airplane, a beat note, at the frequency to which the audio-amplifier stage is tuned, will be produced at the instant the motor-driven condenser 7 causes the receiver to generate oscillations which differ in frequency from the incoming signal by the required amount. The consequent diminution of the plate-current in the control-tube 19 will permit the fast relay 24 to drop out.

As soon as the fast relay 24 drops out, an energizing circuit through ground is completed for the second fast relay 70,

which draws up to complete an energizing circuit through ground for the slow relay 75. The motor-control circuit is accordingly broken at the back-contact 92 of the slow relay 75 and, at the same time, an energizing circuit for the second slow relay 81 is partially completed at the front contact 77. The slow relay 81 is not supplied with potential at this time, however, since the energizing circuit therefor is now broken at the back contact 78 of the second fast relay 7 Simultaneously with the completion. of the energizing circuit for the first slow relay 75, potential is applied through ground to the solenoid 86 by way of the front contact 83 of the second fast relay 79, causing the core 87 to slowly rise and force the armature 90 against the fixed contact 91 to complete an energizing circuit through ground for the f1ood-light control relay 53.

The light-control relay 53, which is of the rapid-closing type, when once actuated, is locked up through the front contact 59 thereof, thus maintaining the power-supply circuit for the lights closed until such time as the locking circuit is broken by manual op eration of the reset button 61.

The purpose of the second slow relay 8]. is to prevent operation of the system by discontinuous interfering signals, such as static, or the like. In the event that the incoming signal is not continuous the fast relays 24 and 70 follow the interruptions, and the energizing circuit for the slow relay 81 is completed through the back contact 78 of the second fast relay 70. Upon supplying current to the slow relay, the armatures 96 and 85 draw up to reestablish the motor-control circuit at the front contact 93, and to break the energizing circuit for the solenoid 86 at the back contact 84. The flood-light control relay is thus prevented from being supplied with energizing current, and the Vernier tuning condenser 7 is again caused to rotate.

It will, accordingly, be apparent from the foregoing description of certain specific embodiments of our invention that we have provided a flood-light control system for airplane landing fields that is thoroughly reliable in operation, and one that iscntirely unaffected by disturbing influences which do not persist over a time interval sufficiently long to permit a selector device to be stepped around to a controlling contact, or to permit a time-delay device of any other well known type to function.

Only negligible effort is required of an aviator in sending out the control signal and substantially no extra equipment need be added to the usual radio transmitting equipment carried by an airplane for communication purposes.

In addition, our improved flood-light control system has the important advantage of being under the control of the aviator even though the landing field itself is entirely outside of visual range. This feature is of immense value in the event that a landing must be made by an aviator who is totally unfamiliar with the terrain surrounding the landing field, inasmuch as it permits him to locate the field while still far away from it.

Manymodifications of our invention, such as the addition of automatic control for the tated bytheprior art, or by the spirit of v the appended claims.

We claim as our invention:

1. In combination, oscillatory radio receiving apparatus, tuning means therefor for causing the receiver to be periodically and sequentially responsive to a plurality of frequencies within a predetermined band, an output circuit for said receiver compris ing means for deriving a direct current from a definite beat-frequency, a source of power, a load, and means responsive to said direct current for controlling the application of power from said source to said load.

2. In combination, oscillatory radio receiving apparatus, tuning means therefor for causing the receiver to be periodically and sequentially responsive to a plurality of frequencies within a predetermined band, an output circuit for said receiver comprising means for deriving a direct current from a definite beat-frequency, a relay responsive to said direct current, the periodicity of said tuning means being such that the tuning range of the receiver is covered in less time than is required for the said relay to release after havin been energized.

3. In com ination, oscillatory radio receiving apparatus, tuning means therefor for causing the receiver to be periodically and sequentially responsive to a plurality of frequencies within a predetermined band, an output circuit for said receiver comprising means for deriving a direct current from a definite beat-frequency, a source of power, a load, and means responsive to said direct current for controlling the application of power from said source to sai load.

4. In combination, radio receiving apparatus including an oscillatory detector, tuning means for causing said apparatus to be periodically and sequentially responsive to a plurality of frequencies within a predetermined band whereby a plurality of beatfrequencies appear in the output of said detector, a source of power, a load, and means preferentially responsive to a single beat frequency for controlling the application of power from said source to said load.

5. In combination, radio receiving apparatus including an oscillatory detector, tuning means for causing said apparatus to be periodically and sequentially responsive to a plurality of frequencies within a predetermined band whereby a plurality of beatfrequencies appear in the output of said de tector, a source of power, a load, means preferentially responsive to a single beat-frequency for controlling the application of power from said source to said load, and time-delay means for preventing the application of said power to said load until said beat-frequency has endured for a predetermined time.

6. Incombination, a field suitable for the landing of aerial vehicles, illuminating means therefor, and control means responsive only to a continuous radio signal of minimum length for controlling said illuminating means, said control means including means for producing a beat note from an incoming radio signal, said last means including an oscillator and means for continuously varying its frequency.

7. In combination, a field suitable for the landing of aerial vehicles, illuminating means therefor, control means responsive only to a continuous radio signal of minimum length for controlling said illuminating means, and means for returning said control means to its original condition if said signal is of less than said minimum length.

8. In combination, a field suitable for the landing of aerial vehicles, illuminating means therefor, and control means responsive only toa continuous radio signal of minimum length for controlling said illuminating means, said control means comprising a selector and stepping magnet therefor, and means for breaking said continuous radio signal into a plurality of impulses for operating said stepping magnet.

9. In combination, a field suitable for the landing of aerial vehicles, illuminating means therefor, and control means responsive only to a continuous radio signal of minimum length for controlling said illuminating means, said control means comprising mechanism responsive to a plurality of impulses and means for breaking said continuous radio signal into a plurality of impulses for operating said mechanism.

10. In combination, a load device, control means responsive only to a continuous radio signal of minimum length for controlling said load device, said control means comprising a continuously operable tuning means whereby a beat note may be obtained with incoming radio signals within a predetermined frequency range, a slow-acting relay responsive tosaid beat note, and means responsive to said beat note for causing said tuning means to cease tuning.

11. In combination, a field suitable for the landing of aerial vehicles,illuminatingmeans therefor, and control means responsive only to a continuous radio signal of minimum length for controlling said illuminating means, said control means comprising a receiver of the superheterodyne type including an oscillator and means for continuously varying the frequency of said oscillator,

and means responsive to & predetermined beat frequency between said incoming signal and the output of said oscillator for preventing further variation in the fre= quency of said oscillator output.

CLARENCE A. BUDDIES.. a RICHARD C. CURTIS. 

